Wellbores may be drilled into a surface location or seabed for a variety of exploratory or extraction purposes. For example, a wellbore may be drilled to access fluids, such as liquid and gaseous hydrocarbons, stored in subterranean formations and to extract the fluids from the formations. Wellbores used to produce or extract fluids may be lined with casing around the walls of the wellbore. A variety of drilling methods and tools may be utilized depending partly on the characteristics of the formation through which the wellbore is drilled.
A drilling system may use a variety of bits in the creation, maintenance, extension, and abandonment of a wellbore. Bits include drilling bits, mills, reamers, hole openers, and other cutting tools. Some drilling systems rotate a bit relative to the wellbore to remove material from the sides and/or bottom of the wellbore. Some bits are used to remove natural material from the surrounding geologic formation to extend or expand the wellbore. Some bits are used to remove material positioned in the wellbore during construction or maintenance of the wellbore. For example, bits are used to remove concrete and/or metal casing from a wellbore during maintenance, creation of a window for lateral drilling in an existing wellbore, or during remediation.
Rotation of the bit relative to the wellbore allows cutting elements on the bit to mechanically remove material from the sides and/or bottom of the wellbore. The engagement between the bit and the sides and/or bottom of the wellbore imparts a torque on the bit. In a conventional drilling system, the torque builds in a length of the drill string similar to a torsional spring. When the stored energy is released, the drill string slips at high rotational speeds. Slipping wastes energy previously transmitted downhole (thereby slowing drilling rates), risks damage to the equipment, and risks injury to operators.
Whirling is the lateral movement of the drill string within a wellbore and can be a harmonic behavior that builds over time. Whirling wastes energy previously transmitted downhole (thereby slowing drilling rates) and can impart high lateral forces on the drill string that can damage the drill string or components connected thereto.